import java.util.Scanner;

public class Speed_artur {

  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    while (true) {
      int d = in.nextInt();
      int s1 = in.nextInt();
      int s2 = in.nextInt();
      if (d == 0 && s1 == 0 && s2 == 0)
        break;

      double time1 = d * 3600.0 / s1;
      double time2 = d * 3600.0 / s2;

      double diff = time1 - time2;
      System.out.printf("%d:%02d:%02d\n", (int) (diff / 3600), (int) (diff % 3600 / 60), (int) (diff % 60 + 0.5));
    }
  }
}